Commit Graph

166 Commits

Author SHA1 Message Date
James Zern
fe80fbbd6b webp-container-spec: add some missing commas
The serial comma change is based on the Chicago Manual of Style
(CMOS), 17th edition.

Change-Id: I642d6eb87492bb671869b25415c59b96b749c798
2023-06-12 22:03:01 -07:00
James Zern
03a7a04892 webp-lossless-bitstream-spec: rm redundant statement
Within the 'Entropy image' subsection, its clear this is what is being
described in the following paragraphs. Remove 'as described below' from
the first sentence.

Bug: webp:611
Change-Id: I365d69c8f6963cd826849ebdd96e46206d38b55d
2023-06-08 11:22:10 -07:00
James Zern
c437c7aace webp-lossless-bitstream-spec: mv up prefix code group def
Move this to the top-level of the "Details" section as prefix codes are
discussed in both "Decoding and Building the Prefix Codes" and "Decoding
of Meta Prefix Codes"

Bug: webp:611
Change-Id: Ide2dfedf081d6c94122ac16ecded968ed760f90c
2023-06-08 11:22:10 -07:00
James Zern
e4f17a31a7 webp-lossless-bitstream-spec: fix section reference
in the Transformations section describing decoding of the transform
data followed by the image data. The section numbers were adjusted by 1
in:
337cf69f webp-lossless-bitstream-spec: mv Nomenclature after Intro

Bug: webp:611
Change-Id: I4eede0d068fabdef51a140a0268436ab6629e8bb
2023-06-08 11:22:10 -07:00
James Zern
e2ecd5e937 webp-lossless-bitstream-spec: clarify ABNF syntax
Give some examples of repetition and binary value notation to limit the
need to follow the ABNF reference.

Bug: webp:611
Change-Id: I5b5a7632f011e1523b4a528653fe3630afba3e3e
2023-06-08 11:22:10 -07:00
James Zern
8b55425a56 webp-lossless-bitstream-spec: refine pixel copy text
in 6.2.3 Decoding Entropy-Coded Image Data.

The copying of distance code pixels cause some confusion during the
AUTH48 portion of the RFC review process.

Bug: webp:611
Change-Id: I78f547ae10c95f180355a4c93ec6d48acdc09141
2023-06-08 11:22:10 -07:00
James Zern
29c9f2d410 webp-lossless-bitstream-spec: minor wording updates
Mostly grammatical and addition/subtraction of commas from the AUTH48
portion of the RFC review process.

The serial comma changes are based on the Chicago Manual of Style
(CMOS), 17th edition.

Bug: webp:611
Change-Id: I5ae2d1cc0196009dbf3a4c2195cc73c2ef809b49
2023-06-08 11:21:55 -07:00
James Zern
7f75c91ced webp-container-spec: fix location of informative msg
preprocessing bits are informative, not the filtering bits.

since:
391f9db9 Ordering of description of bits in container spec

Change-Id: I1c0da963074ce9cf4d33a13b4b36c9421b3e3b9d
2023-06-06 22:09:41 -07:00
James Zern
f6499943c4 webp-container-spec: consistently quote FourCCs
from the AUTH48 portion of the RFC review process

Change-Id: I3aad4b32c95517735e98ffa0120228ee24be6a4d
2023-06-06 18:47:20 -07:00
James Zern
49918af32b webp-container-spec: minor wording updates
Mostly grammatical and addition/subtraction of commas from the AUTH48
portion of the RFC review process.

The serial comma changes are based on the Chicago Manual of Style
(CMOS), 17th edition.

Change-Id: Ic75abf2e53e09c8a849e28e9c40e16c127515287
2023-06-05 18:26:34 -07:00
James Zern
15b365083d doc/webp-container-spec: rm future codec comment
From the compression standpoint the file format is fixed at this point.

Change-Id: I788fcf7106e4840bf2f9950dfb099a7bab88b3bf
2023-05-26 15:48:31 -07:00
James Zern
c369c4bf0b doc/webp-lossless-bitstream-spec: improve link text
Reference the section by number, rather than 'this section'. Fixes a
lint warning:

Style notice: Write unique, descriptive link text that makes sense
without the surrounding text. Don't use phrases such as this document,
this article, or click here.
https://developers.google.com/style/link-text?hl=en#write-link-text

Change-Id: Iab33e4980528dddb5eed4404d25a4a746705131a
2023-05-26 15:48:28 -07:00
James Zern
1de35f476b doc/webp-container-spec: don't use 'currently'
Provide examples of formats that WebP performs better than.

https://developers.google.com/style/timeless-documentation

Change-Id: I4ead60be349d8650478788484989bde9ff18f6b6
2023-05-26 15:48:26 -07:00
James Zern
bb06a16ed1 doc/webp-container-spec: prefer present tense
https://developers.google.com/style/tense

Change-Id: I0cd4e1431cddc340adf5634c07f0c60635b3d4f2
2023-05-26 15:48:23 -07:00
James Zern
9f38b71e01 doc/webp-lossless-bitstream-spec: prefer present tense
https://developers.google.com/style/tense

Change-Id: I1151ad0f585afd388920e6910a30aca4c2d0cc32
2023-05-26 15:48:17 -07:00
James Zern
7acb6b829a doc/webp-container-spec: avoid i.e. & e.g.
Using 'that is' or 'for example' is recommended:
https://developers.google.com/style/abbreviations#dont-use

Change-Id: I25b45f5b41687dfbd25a0fbea4978d6bc8e44ad2
2023-05-26 15:48:12 -07:00
James Zern
4967e7cd78 doc/webp-lossless-bitstream-spec: avoid i.e. & e.g.
Using 'that is' or 'for example' is recommended:
https://developers.google.com/style/abbreviations#dont-use

Change-Id: I5d0dad2ee7ae5ebaf73661d5d79a4a2f1dc1802a
2023-05-26 15:48:09 -07:00
Jyrki Alakuijala
428588ef90 clarify single leaf node trees and use of canonical prefix coding
remove AMENDED-notes (the last functional spec change to match with the
implementation is from 2014, other amendments are clarifications)

Bug: webp:581
Change-Id: Ic47739be0fd5a975fd734d6813567ca615304f1d
2023-05-25 17:25:48 -07:00
James Zern
17e0ef1da5 webp-lossless-bitstream-spec: remove use of 'dynamics'
when bit width or precision are meant.

Change-Id: I89c2279e99b02c3e8a3bf39860364d2ce6d909c8
2023-05-12 15:10:30 -07:00
James Zern
84d04c4845 webp-lossless-bitstream-spec: add missing bits to ABNF
alpha-is-used and the version number were missing before 'image-stream'

spotted by thakis@

Change-Id: I7a4f1d2e0f0962bb1a79a0400c229738159d88a5
2023-04-13 12:13:34 -07:00
James Zern
4c3d7018c0 webp-lossless-bitstream-spec: condense normal-prefix-code
Have this match simple-prefix-code and redirect to "Normal Code Length
Code" as the added indirection to 'code-length-code' and the undefined
'encoded-code-lengths' doesn't add much.

spotted by thakis@

Change-Id: Icd6b64a47c4e0001e93271d9ae5585be4a6d5906
2023-04-10 17:22:55 -07:00
James Zern
a6a09b3296 webp-lossless-bitstream-spec: fix 2 code typos
- add missing '(' in DIV_ROUND_UP
- in 6.2.2, rename 'pos' variable reference to match definition
  ('position')

spotted by thakis@

Change-Id: Ida3ed281c2c753ebbb0e1eb3c4ed04dadc79ca24
2023-04-10 17:18:52 -07:00
James Zern
2fe27bb96d img2webp: normalize help output
this makes the output from img2webp and the ordering in doc/tools.md and
man/img2webp.1 consistent

Change-Id: Ic389aaa29c20128f2b87f231be383094602f125b
2023-03-17 15:37:55 -07:00
James Zern
24bed3d9fb cwebp: reflow -near_lossless help text
this matches the output from img2webp added in:
0825faa4 img2webp: add -sharp_yuv/-near_lossless

Change-Id: I329ccd796d7e9bee36de1429fceafe83d7dc5532
2023-03-17 15:17:31 -07:00
jzern@google.com
0825faa4c1 img2webp: add -sharp_yuv/-near_lossless
Both are global settings. Modifying them at the frame level is left as a
follow up based on need.

Bug: b/272739498
Change-Id: If15256c052f73fe3df56be5e0095e76d9870cc0f
2023-03-17 09:35:29 -07:00
James Zern
d3e151fc03 doc/api.md,webp_js/README.md: Webp -> WebP
Change-Id: Ib30d008b5750d2e4064aaf478db6f5bc7aa5902e
2022-12-15 18:14:19 -08:00
James Zern
e5fe2cfc1b webp-lossless-bitstream-spec,cosmetics: reflow paragraphs
Change-Id: Ifd7472fe0678b45efc62faa66de8e8dc2e9931e3
2022-11-22 11:38:01 -08:00
James Zern
0ceeeab987 webp-lossless-bitstream-spec: add amendment note
for fixes to the distance_map pseudo-code, the inverse color transform
description and the num_code_lengths check.

Bug: webp:448
Bug: webp:551
Change-Id: Id7e791b97704dd64bb9519657ce48b92cb457ae4
2022-11-22 11:38:01 -08:00
James Zern
607611cd86 Merge "webp-container-spec: normalize section title case" into main 2022-11-22 19:35:41 +00:00
James Zern
f853685e13 lossless: SUBTRACT_GREEN -> SUBTRACT_GREEN_TRANSFORM
this makes the name of the TransformType enum value match the other
members

Bug: webp:448
Change-Id: I85b2f615f97b40fc6d544197cccfb7189dcf4fc0
2022-11-21 16:48:51 -08:00
James Zern
786497e48a webp-lossless-bitstream-spec: fix inv color txfm description
The prose describing the process was missed in:
44dd765d webp-lossless-bitstream-spec: fix ColorTransform impl

Bug: webp:448
Bug: webp:551
Change-Id: If5fb95103ffedeed113e3ad62510f3a19bfd280e
2022-11-21 16:48:51 -08:00
James Zern
c6ac672dbc webp-lossless-bitstream-spec: fix num_code_lengths check
in the 'Normal Code Length Code' description the number of valid code
lengths is 19, not 18.

Bug: webp:448
Bug: webp:551
Change-Id: Id929604e1d771cb09b2d0ac617e83f21077f21de
2022-11-21 16:48:51 -08:00
James Zern
b5700efb70 webp-lossless-bitstream-spec,cosmetics: grammar/capitalization
Bug: webp:448
Change-Id: I2d6cc66b45342716fdba7792c570510601432109
2022-11-21 16:48:41 -08:00
James Zern
d8ed8c117c webp-container-spec: normalize section title case
Use 'title case' as recommended in RFC 7322 (Section 3.4 Capitalization)

Bug: webp:448
Change-Id: I9762402499eb58acbe9ccb75f4f8d2b9c3e9b26b
2022-11-21 10:53:13 -08:00
James Zern
52ec0b8f61 Merge changes Ie975dbb5,Ifc8c93af,I6ca7c5d6,I2e8d66f5,I152477b8 into main
* changes:
  webp-lossless-bitstream-spec,cosmetics: reflow abstract
  webp-lossless-bitstream-spec: reword abstract re alpha
  webp-lossless-bitstream-spec,cosmetics: normalize range syntax
  webp-lossless-bitstream-spec: limit dist map lut to 69 cols
  webp-lossless-bitstream-spec: fix dist mapping example
2022-11-18 18:28:15 +00:00
James Zern
5097ef6255 webp-container-spec,cosmetics: grammar/capitalization
Bug: webp:448
Change-Id: I8b5e218df95436b6b8b2ecc751c70015d46fe7a0
2022-11-17 19:13:39 -08:00
James Zern
e3ba2b1f5b webp-lossless-bitstream-spec,cosmetics: reflow abstract
Bug: webp:448
Change-Id: Ie975dbb52687c6c068b029fc8f84db8cf189523a
2022-11-17 18:25:13 -08:00
James Zern
1e8e3ded21 webp-lossless-bitstream-spec: reword abstract re alpha
'zero alpha pixels' was a bit hard to parse; replace this with something
more explicit

Bug: webp:448
Change-Id: Ifc8c93af5520ffdafc58e3fc311dfb4cb19626e9
2022-11-17 18:22:56 -08:00
James Zern
017cb6fa94 webp-container-spec,cosmetics: normalize range syntax
this makes the syntax in this document consistent with
webp-lossless-bitstream-spec.txt

[N-M] -> [N..M]

Bug: webp:448
Change-Id: Iebf39eefb7d3c081a3d10e2804ee215c3aed6b79
2022-11-17 18:13:32 -08:00
James Zern
f6a4684ba8 webp-lossless-bitstream-spec,cosmetics: normalize range syntax
[N-M], [N, M] -> [N..M]

these were missed in:
e74f8a62 webp-lossless-bitstream-spec,cosmetics: normalize range syntax

Bug: webp:448
Change-Id: I6ca7c5d6b0473fdf3de0c6dba00b0f1e3da46a23
2022-11-17 18:06:49 -08:00
James Zern
54ebd5a375 webp-lossless-bitstream-spec: limit dist map lut to 69 cols
this is similar to an earlier change for most of the code examples:
  7a0a9935 doc/*.txt: restrict code to 69 columns

some renderers may limit output to 72 and use a 3 space indent; this
avoids overflowing into the margin

Bug: webp:448
Change-Id: I2e8d66f598889c7bd824e911ea01fd70f98a4130
2022-11-17 18:06:45 -08:00
James Zern
44741f9c58 webp-lossless-bitstream-spec: fix dist mapping example
The distance code read from the bitstream is reduced by 1 before doing
the lookup. The prose describing the lookup was correct, the pseudocode
failed to subtract 1 and used x/y instead of xi/yi from the lookup.

Bug: webp:448
Change-Id: I152477b888c26a0473a35373d3d331fddd14237f
2022-11-17 18:06:31 -08:00
James Zern
d34f9b99b9 Merge "webp-lossless-bitstream-spec: convert BNF to ABNF" into main 2022-10-15 02:01:48 +00:00
James Zern
83270c7f89 webp-container-spec: add prose for rendering process
this is given in addition to the pseudocode, which has been corrected in
the process

based on comments in:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I96bc063c2a71572ff61609a731a9c4e8edc2b971
2022-10-13 19:34:54 -07:00
James Zern
73b19b64fd webp-container-spec: note reserved fields MUST be ignored
based on comments in:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I45880467d8955389a2ef657beca9d734da223457
2022-10-13 19:34:54 -07:00
James Zern
57101d3fc5 webp-lossless-bitstream-spec: improve 'small' color table stmt
this is defined earlier as 16 or fewer unique values

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: If9e18e5aaec3641e477c2bb68dacc0a4fd029cfb
2022-10-13 19:34:54 -07:00
James Zern
dfd32e4592 webp-container-spec: remove redundant sentence
in the note regarding metadata the possibility of multiple XMP/EXIF
chunks was already covered in the previous sentences.

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I6ee938e4d95bda1b144d3175fbf9f9296cf23352
2022-10-13 19:34:54 -07:00
James Zern
8a6185dd27 doc/webp-*: fix some punctuation, grammar
based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I0a410b28b7b62fb4552ea3db444743be61469fe8
2022-10-13 19:34:54 -07:00
James Zern
72776530d8 webp-lossless-bitstream-spec: convert BNF to ABNF
this has a better canonical reference [1] and is preferred in IETF docs

[1] https://www.rfc-editor.org/rfc/rfc5234

Bug: webp:448
Change-Id: I3f0bd34d3ca4c62b255d5d6cbae0c55e2940dfb5
2022-10-12 16:55:46 -07:00
James Zern
3ed2b27517 webp-container-spec: clarify background color note
replace ...a transparency value (alpha)... with clearer text

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I79157b669c4317ebfc4f8434ee38f2666d1559ec
2022-10-11 15:05:33 -07:00